Prepare a medium-hot fire in a charcoal grill with a cover, or preheat a gas grill to medium-high.

To make the spread, combine rhubarb, raising, onion, sugar and vinegar in a medium saucepan. Cook until thick. Continue as it thickens to prevent sticking. Add spices and cook 5 minutes longer. Cover and set aside.

To make the patties, combine all ingredients, handling as little as possible. Shape into 6 patties to fit the buns. Loosely cover with plastic wrap and set aside.

To prepare the buns, slice each in half. Combine melted butter with spices. Brush cut sides of buns with butter mixture. Cover and set aside.

When the grill is ready, brush the grill rack with vegetable oil. Place the patties on the rack, cover and cook, turning once until done to preference, 8 to 10 minutes on each side.

To assemble the burgers, place patty on bottom bun. Top with sweet and sour cabbage. Spoon spread over cabbage. Add the top bun and serve.